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Gene Variations Affect PTSD Risk for Adults Abused as Children

Certain gene variations, a new study has found, make adults who were abused as children more likely to develop posttraumatic stress disorder (PTSD) after a traumatic event.

Researchers have known that adults who experienced trauma in
childhood are more likely to develop PTSD after a traumatic event
later in life. But scientists believe there’s also a genetic
component to the disorder. Some people are more likely than others
to develop PTSD after being exposed to similar levels of trauma.
Inherited genetic variations are estimated to account for 30-40%
of the risk of developing PTSD, although the genes involved haven’t
yet been identified.

A research team headed by Dr. Elisabeth Binder and Dr. Kerry
J. Ressler of Emory University set out to explore the interaction
between environmental and genetic influences on the development
of PTSD. The researchers surveyed 900 people from poor, urban
neighborhoods. The participants were between 18 and 81 years
old and were primarily African-American. Many had severe traumatic
experiences in childhood and later other kinds of traumatic incidents
as adults.

The researchers also examined 765 of the participants for variations
in a gene called FKBP5, which plays a role in regulating
the response to stress. Their work was supported primarily by
NIH’s National Institute of Mental Health (NIMH), with
additional funding from NIH’s National Institute on Drug
Abuse (NIDA), National Center for Research Resources (NCRR) and
others.

The results appeared in the March 19, 2008, issue of the Journal
of the American Medical Association. The researchers found
that adults with a history of child abuse—almost 30%
of the people in the study—developed more than twice
the number of PTSD symptoms when they underwent later traumas
as those who weren't abused in childhood.

Among the participants who weren’t abused in childhood,
the researchers found no links between FKBP5 and the
likelihood of developing PTSD. However, for those with
a history of child abuse, 4 FKBP5 variations affected
the likelihood that they would develop PTSD after a later trauma.

These findings suggest that, for people with certain genetic
variants, early-life abuse can result in potent changes to the
stress response system as it develops. “These results are
early and will need to be replicated, but they support the hypothesis
that combinations of genes and environmental factors affect the
risk for stress-related disorders like PTSD,” Ressler said.

“Untangling complex interactions between genetic variations
and environmental factors can help us learn how to predict more
accurately who's at risk of disorders like PTSD,” said NIMH
Director Dr. Thomas R. Insel. “It can help us learn which
prevention and treatment strategies are likely to work best for
each person.”